4.3BSD/usr/src/etc/inetd.c
/*
* Copyright (c) 1983 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/
#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1983 Regents of the University of California.\n\
All rights reserved.\n";
#endif not lint
#ifndef lint
static char sccsid[] = "@(#)inetd.c 5.6 (Berkeley) 4/29/86";
#endif not lint
/*
* Inetd - Internet super-server
*
* This program invokes all internet services as needed.
* connection-oriented services are invoked each time a
* connection is made, by creating a process. This process
* is passed the connection as file descriptor 0 and is
* expected to do a getpeername to find out the source host
* and port.
*
* Datagram oriented services are invoked when a datagram
* arrives; a process is created and passed a pending message
* on file descriptor 0. Datagram servers may either connect
* to their peer, freeing up the original socket for inetd
* to receive further messages on, or ``take over the socket'',
* processing all arriving datagrams and, eventually, timing
* out. The first type of server is said to be ``multi-threaded'';
* the second type of server ``single-threaded''.
*
* Inetd uses a configuration file which is read at startup
* and, possibly, at some later time in response to a hangup signal.
* The configuration file is ``free format'' with fields given in the
* order shown below. Continuation lines for an entry must being with
* a space or tab. All fields must be present in each entry.
*
* service name must be in /etc/services
* socket type stream/dgram/raw/rdm/seqpacket
* protocol must be in /etc/protocols
* wait/nowait single-threaded/multi-threaded
* user user to run daemon as
* server program full path name
* server program arguments maximum of MAXARGS (5)
*
* Comment lines are indicated by a `#' in column 1.
*/
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#include <netdb.h>
#include <syslog.h>
#include <pwd.h>
#define TOOMANY 40 /* don't start more than TOOMANY */
#define CNT_INTVL 60 /* servers in CNT_INTVL sec. */
#define RETRYTIME (60*10) /* retry after bind or server fail */
#define SIGBLOCK (sigmask(SIGCHLD)|sigmask(SIGHUP)|sigmask(SIGALRM))
extern int errno;
int reapchild(), retry();
char *index();
char *malloc();
int debug = 0;
int nsock, maxsock;
fd_set allsock;
int options;
int timingout;
struct servent *sp;
struct servtab {
char *se_service; /* name of service */
int se_socktype; /* type of socket to use */
char *se_proto; /* protocol used */
short se_wait; /* single threaded server */
short se_checked; /* looked at during merge */
char *se_user; /* user name to run as */
struct biltin *se_bi; /* if built-in, description */
char *se_server; /* server program */
#define MAXARGV 5
char *se_argv[MAXARGV+1]; /* program arguments */
int se_fd; /* open descriptor */
struct sockaddr_in se_ctrladdr;/* bound address */
int se_count; /* number started since se_time */
struct timeval se_time; /* start of se_count */
struct servtab *se_next;
} *servtab;
int echo_stream(), discard_stream(), machtime_stream();
int daytime_stream(), chargen_stream();
int echo_dg(), discard_dg(), machtime_dg(), daytime_dg(), chargen_dg();
struct biltin {
char *bi_service; /* internally provided service name */
int bi_socktype; /* type of socket supported */
short bi_fork; /* 1 if should fork before call */
short bi_wait; /* 1 if should wait for child */
int (*bi_fn)(); /* function which performs it */
} biltins[] = {
/* Echo received data */
"echo", SOCK_STREAM, 1, 0, echo_stream,
"echo", SOCK_DGRAM, 0, 0, echo_dg,
/* Internet /dev/null */
"discard", SOCK_STREAM, 1, 0, discard_stream,
"discard", SOCK_DGRAM, 0, 0, discard_dg,
/* Return 32 bit time since 1970 */
"time", SOCK_STREAM, 0, 0, machtime_stream,
"time", SOCK_DGRAM, 0, 0, machtime_dg,
/* Return human-readable time */
"daytime", SOCK_STREAM, 0, 0, daytime_stream,
"daytime", SOCK_DGRAM, 0, 0, daytime_dg,
/* Familiar character generator */
"chargen", SOCK_STREAM, 1, 0, chargen_stream,
"chargen", SOCK_DGRAM, 0, 0, chargen_dg,
0
};
#define NUMINT (sizeof(intab) / sizeof(struct inent))
char *CONFIG = "/etc/inetd.conf";
char **Argv;
char *LastArg;
main(argc, argv, envp)
int argc;
char *argv[], *envp[];
{
register struct servtab *sep;
register struct passwd *pwd;
char *cp, buf[50];
int pid, i, dofork;
struct sigvec sv;
Argv = argv;
if (envp == 0 || *envp == 0)
envp = argv;
while (*envp)
envp++;
LastArg = envp[-1] + strlen(envp[-1]);
argc--, argv++;
while (argc > 0 && *argv[0] == '-') {
for (cp = &argv[0][1]; *cp; cp++) switch (*cp) {
case 'd':
debug = 1;
options |= SO_DEBUG;
break;
default:
fprintf(stderr,
"inetd: Unknown flag -%c ignored.\n", *cp);
break;
}
nextopt:
argc--, argv++;
}
if (argc > 0)
CONFIG = argv[0];
#ifndef DEBUG
if (fork())
exit(0);
{ int s;
for (s = 0; s < 10; s++)
(void) close(s);
}
(void) open("/", O_RDONLY);
(void) dup2(0, 1);
(void) dup2(0, 2);
{ int tt = open("/dev/tty", O_RDWR);
if (tt > 0) {
ioctl(tt, TIOCNOTTY, (char *)0);
close(tt);
}
}
#endif
openlog("inetd", LOG_PID | LOG_NOWAIT, LOG_DAEMON);
bzero((char *)&sv, sizeof(sv));
sv.sv_mask = SIGBLOCK;
sv.sv_handler = retry;
sigvec(SIGALRM, &sv, (struct sigvec *)0);
config();
sv.sv_handler = config;
sigvec(SIGHUP, &sv, (struct sigvec *)0);
sv.sv_handler = reapchild;
sigvec(SIGCHLD, &sv, (struct sigvec *)0);
for (;;) {
int s, ctrl, n;
fd_set readable;
while (nsock == 0)
sigpause(0);
readable = allsock;
if ((n = select(maxsock + 1, &readable, (fd_set *)0,
(fd_set *)0, (struct timeval *)0)) <= 0) {
if (n < 0 && errno != EINTR)
syslog(LOG_WARNING, "select: %m\n");
sleep(1);
continue;
}
for (sep = servtab; n && sep; sep = sep->se_next)
if (FD_ISSET(sep->se_fd, &readable)) {
n--;
if (debug)
fprintf(stderr, "someone wants %s\n", sep->se_service);
if (!sep->se_wait && sep->se_socktype == SOCK_STREAM) {
ctrl = accept(sep->se_fd, (struct sockaddr *)0,
(int *)0);
if (debug)
fprintf(stderr, "accept, ctrl %d\n", ctrl);
if (ctrl < 0) {
if (errno == EINTR)
continue;
syslog(LOG_WARNING, "accept: %m");
continue;
}
} else
ctrl = sep->se_fd;
(void) sigblock(SIGBLOCK);
pid = 0;
dofork = (sep->se_bi == 0 || sep->se_bi->bi_fork);
if (dofork) {
if (sep->se_count++ == 0)
(void)gettimeofday(&sep->se_time,
(struct timezone *)0);
else if (sep->se_count >= TOOMANY) {
struct timeval now;
(void)gettimeofday(&now, (struct timezone *)0);
if (now.tv_sec - sep->se_time.tv_sec >
CNT_INTVL) {
sep->se_time = now;
sep->se_count = 1;
} else {
syslog(LOG_ERR,
"%s/%s server failing (looping), service terminated\n",
sep->se_service, sep->se_proto);
FD_CLR(sep->se_fd, &allsock);
(void) close(sep->se_fd);
sep->se_fd = -1;
sep->se_count = 0;
nsock--;
sigsetmask(0);
if (!timingout) {
timingout = 1;
alarm(RETRYTIME);
}
continue;
}
}
pid = fork();
}
if (pid < 0) {
if (!sep->se_wait && sep->se_socktype == SOCK_STREAM)
close(ctrl);
sigsetmask(0);
sleep(1);
continue;
}
if (pid && sep->se_wait) {
sep->se_wait = pid;
FD_CLR(sep->se_fd, &allsock);
nsock--;
}
sigsetmask(0);
if (pid == 0) {
#ifdef DEBUG
int tt;
if (dofork && (tt = open("/dev/tty", O_RDWR)) > 0) {
ioctl(tt, TIOCNOTTY, 0);
close(tt);
}
#endif
if (dofork)
for (i = getdtablesize(); --i > 2; )
if (i != ctrl)
close(i);
if (sep->se_bi)
(*sep->se_bi->bi_fn)(ctrl, sep);
else {
dup2(ctrl, 0);
close(ctrl);
dup2(0, 1);
dup2(0, 2);
if ((pwd = getpwnam(sep->se_user)) == NULL) {
syslog(LOG_ERR,
"getpwnam: %s: No such user",
sep->se_user);
if (sep->se_socktype != SOCK_STREAM)
recv(0, buf, sizeof (buf), 0);
_exit(1);
}
if (pwd->pw_uid) {
(void) setgid((gid_t)pwd->pw_gid);
initgroups(pwd->pw_name, pwd->pw_gid);
(void) setuid((uid_t)pwd->pw_uid);
}
if (debug)
fprintf(stderr, "%d execl %s\n",
getpid(), sep->se_server);
execv(sep->se_server, sep->se_argv);
if (sep->se_socktype != SOCK_STREAM)
recv(0, buf, sizeof (buf), 0);
syslog(LOG_ERR, "execv %s: %m", sep->se_server);
_exit(1);
}
}
if (!sep->se_wait && sep->se_socktype == SOCK_STREAM)
close(ctrl);
}
}
}
reapchild()
{
union wait status;
int pid;
register struct servtab *sep;
for (;;) {
pid = wait3(&status, WNOHANG, (struct rusage *)0);
if (pid <= 0)
break;
if (debug)
fprintf(stderr, "%d reaped\n", pid);
for (sep = servtab; sep; sep = sep->se_next)
if (sep->se_wait == pid) {
if (status.w_status)
syslog(LOG_WARNING,
"%s: exit status 0x%x",
sep->se_server, status);
if (debug)
fprintf(stderr, "restored %s, fd %d\n",
sep->se_service, sep->se_fd);
FD_SET(sep->se_fd, &allsock);
nsock++;
sep->se_wait = 1;
}
}
}
config()
{
register struct servtab *sep, *cp, **sepp;
struct servtab *getconfigent(), *enter();
int omask;
if (!setconfig()) {
syslog(LOG_ERR, "%s: %m", CONFIG);
return;
}
for (sep = servtab; sep; sep = sep->se_next)
sep->se_checked = 0;
while (cp = getconfigent()) {
for (sep = servtab; sep; sep = sep->se_next)
if (strcmp(sep->se_service, cp->se_service) == 0 &&
strcmp(sep->se_proto, cp->se_proto) == 0)
break;
if (sep != 0) {
int i;
omask = sigblock(SIGBLOCK);
if (cp->se_bi == 0)
sep->se_wait = cp->se_wait;
#define SWAP(a, b) { char *c = a; a = b; b = c; }
if (cp->se_user)
SWAP(sep->se_user, cp->se_user);
if (cp->se_server)
SWAP(sep->se_server, cp->se_server);
for (i = 0; i < MAXARGV; i++)
SWAP(sep->se_argv[i], cp->se_argv[i]);
sigsetmask(omask);
freeconfig(cp);
} else
sep = enter(cp);
sep->se_checked = 1;
sp = getservbyname(sep->se_service, sep->se_proto);
if (sp == 0) {
syslog(LOG_ERR, "%s/%s: unknown service",
sep->se_service, sep->se_proto);
continue;
}
if (sp->s_port != sep->se_ctrladdr.sin_port) {
sep->se_ctrladdr.sin_port = sp->s_port;
if (sep->se_fd != -1)
(void) close(sep->se_fd);
sep->se_fd = -1;
}
if (sep->se_fd == -1)
setup(sep);
}
endconfig();
/*
* Purge anything not looked at above.
*/
omask = sigblock(SIGBLOCK);
sepp = &servtab;
while (sep = *sepp) {
if (sep->se_checked) {
sepp = &sep->se_next;
continue;
}
*sepp = sep->se_next;
if (sep->se_fd != -1) {
FD_CLR(sep->se_fd, &allsock);
nsock--;
(void) close(sep->se_fd);
}
freeconfig(sep);
free((char *)sep);
}
(void) sigsetmask(omask);
}
retry()
{
register struct servtab *sep;
timingout = 0;
for (sep = servtab; sep; sep = sep->se_next)
if (sep->se_fd == -1)
setup(sep);
}
setup(sep)
register struct servtab *sep;
{
int on = 1;
if ((sep->se_fd = socket(AF_INET, sep->se_socktype, 0)) < 0) {
syslog(LOG_ERR, "%s/%s: socket: %m",
sep->se_service, sep->se_proto);
return;
}
#define turnon(fd, opt) \
setsockopt(fd, SOL_SOCKET, opt, (char *)&on, sizeof (on))
if (strcmp(sep->se_proto, "tcp") == 0 && (options & SO_DEBUG) &&
turnon(sep->se_fd, SO_DEBUG) < 0)
syslog(LOG_ERR, "setsockopt (SO_DEBUG): %m");
if (turnon(sep->se_fd, SO_REUSEADDR) < 0)
syslog(LOG_ERR, "setsockopt (SO_REUSEADDR): %m");
#undef turnon
if (bind(sep->se_fd, &sep->se_ctrladdr,
sizeof (sep->se_ctrladdr)) < 0) {
syslog(LOG_ERR, "%s/%s: bind: %m",
sep->se_service, sep->se_proto);
(void) close(sep->se_fd);
sep->se_fd = -1;
if (!timingout) {
timingout = 1;
alarm(RETRYTIME);
}
return;
}
if (sep->se_socktype == SOCK_STREAM)
listen(sep->se_fd, 10);
FD_SET(sep->se_fd, &allsock);
nsock++;
if (sep->se_fd > maxsock)
maxsock = sep->se_fd;
}
struct servtab *
enter(cp)
struct servtab *cp;
{
register struct servtab *sep;
int omask;
char *strdup();
sep = (struct servtab *)malloc(sizeof (*sep));
if (sep == (struct servtab *)0) {
syslog(LOG_ERR, "Out of memory.");
exit(-1);
}
*sep = *cp;
sep->se_fd = -1;
omask = sigblock(SIGBLOCK);
sep->se_next = servtab;
servtab = sep;
sigsetmask(omask);
return (sep);
}
FILE *fconfig = NULL;
struct servtab serv;
char line[256];
char *skip(), *nextline();
setconfig()
{
if (fconfig != NULL) {
fseek(fconfig, 0L, L_SET);
return (1);
}
fconfig = fopen(CONFIG, "r");
return (fconfig != NULL);
}
endconfig()
{
if (fconfig == NULL)
return;
fclose(fconfig);
fconfig = NULL;
}
struct servtab *
getconfigent()
{
register struct servtab *sep = &serv;
char *cp, *arg;
int argc;
more:
while ((cp = nextline(fconfig)) && *cp == '#')
;
if (cp == NULL)
return ((struct servtab *)0);
sep->se_service = strdup(skip(&cp));
arg = skip(&cp);
if (strcmp(arg, "stream") == 0)
sep->se_socktype = SOCK_STREAM;
else if (strcmp(arg, "dgram") == 0)
sep->se_socktype = SOCK_DGRAM;
else if (strcmp(arg, "rdm") == 0)
sep->se_socktype = SOCK_RDM;
else if (strcmp(arg, "seqpacket") == 0)
sep->se_socktype = SOCK_SEQPACKET;
else if (strcmp(arg, "raw") == 0)
sep->se_socktype = SOCK_RAW;
else
sep->se_socktype = -1;
sep->se_proto = strdup(skip(&cp));
arg = skip(&cp);
sep->se_wait = strcmp(arg, "wait") == 0;
sep->se_user = strdup(skip(&cp));
sep->se_server = strdup(skip(&cp));
if (strcmp(sep->se_server, "internal") == 0) {
register struct biltin *bi;
for (bi = biltins; bi->bi_service; bi++)
if (bi->bi_socktype == sep->se_socktype &&
strcmp(bi->bi_service, sep->se_service) == 0)
break;
if (bi->bi_service == 0) {
syslog(LOG_ERR, "internal service %s unknown\n",
sep->se_service);
goto more;
}
sep->se_bi = bi;
sep->se_wait = bi->bi_wait;
}
argc = 0;
for (arg = skip(&cp); cp; arg = skip(&cp))
if (argc < MAXARGV)
sep->se_argv[argc++] = strdup(arg);
while (argc <= MAXARGV)
sep->se_argv[argc++] = NULL;
return (sep);
}
freeconfig(cp)
register struct servtab *cp;
{
int i;
if (cp->se_service)
free(cp->se_service);
if (cp->se_proto)
free(cp->se_proto);
if (cp->se_user)
free(cp->se_user);
if (cp->se_server)
free(cp->se_server);
for (i = 0; i < MAXARGV; i++)
if (cp->se_argv[i])
free(cp->se_argv[i]);
}
char *
skip(cpp)
char **cpp;
{
register char *cp = *cpp;
char *start;
again:
while (*cp == ' ' || *cp == '\t')
cp++;
if (*cp == '\0') {
char c;
c = getc(fconfig);
ungetc(c, fconfig);
if (c == ' ' || c == '\t')
if (cp = nextline(fconfig))
goto again;
*cpp = (char *)0;
return ((char *)0);
}
start = cp;
while (*cp && *cp != ' ' && *cp != '\t')
cp++;
if (*cp != '\0')
*cp++ = '\0';
*cpp = cp;
return (start);
}
char *
nextline(fd)
FILE *fd;
{
char *cp;
if (fgets(line, sizeof (line), fd) == NULL)
return ((char *)0);
cp = index(line, '\n');
if (cp)
*cp = '\0';
return (line);
}
char *
strdup(cp)
char *cp;
{
char *new;
if (cp == NULL)
cp = "";
new = malloc((unsigned)(strlen(cp) + 1));
if (new == (char *)0) {
syslog(LOG_ERR, "Out of memory.");
exit(-1);
}
strcpy(new, cp);
return (new);
}
setproctitle(a, s)
char *a;
int s;
{
int size;
register char *cp;
struct sockaddr_in sin;
char buf[80];
cp = Argv[0];
size = sizeof(sin);
if (getpeername(s, &sin, &size) == 0)
sprintf(buf, "-%s [%s]", a, inet_ntoa(sin.sin_addr));
else
sprintf(buf, "-%s", a);
strncpy(cp, buf, LastArg - cp);
cp += strlen(cp);
while (cp < LastArg)
*cp++ = ' ';
}
/*
* Internet services provided internally by inetd:
*/
/* ARGSUSED */
echo_stream(s, sep) /* Echo service -- echo data back */
int s;
struct servtab *sep;
{
char buffer[BUFSIZ];
int i;
setproctitle("echo", s);
while ((i = read(s, buffer, sizeof(buffer))) > 0 &&
write(s, buffer, i) > 0)
;
exit(0);
}
/* ARGSUSED */
echo_dg(s, sep) /* Echo service -- echo data back */
int s;
struct servtab *sep;
{
char buffer[BUFSIZ];
int i, size;
struct sockaddr sa;
size = sizeof(sa);
if ((i = recvfrom(s, buffer, sizeof(buffer), 0, &sa, &size)) < 0)
return;
(void) sendto(s, buffer, i, 0, &sa, sizeof(sa));
}
/* ARGSUSED */
discard_stream(s, sep) /* Discard service -- ignore data */
int s;
struct servtab *sep;
{
char buffer[BUFSIZ];
setproctitle("discard", s);
while (1) {
while (read(s, buffer, sizeof(buffer)) > 0)
;
if (errno != EINTR)
break;
}
exit(0);
}
/* ARGSUSED */
discard_dg(s, sep) /* Discard service -- ignore data */
int s;
struct servtab *sep;
{
char buffer[BUFSIZ];
(void) read(s, buffer, sizeof(buffer));
}
#include <ctype.h>
#define LINESIZ 72
char ring[128];
char *endring;
initring()
{
register int i;
endring = ring;
for (i = 0; i <= 128; ++i)
if (isprint(i))
*endring++ = i;
}
/* ARGSUSED */
chargen_stream(s, sep) /* Character generator */
int s;
struct servtab *sep;
{
char text[LINESIZ+2];
register int i;
register char *rp, *rs, *dp;
setproctitle("discard", s);
if (endring == 0)
initring();
for (rs = ring; ; ++rs) {
if (rs >= endring)
rs = ring;
rp = rs;
dp = text;
i = MIN(LINESIZ, endring - rp);
bcopy(rp, dp, i);
dp += i;
if ((rp += i) >= endring)
rp = ring;
if (i < LINESIZ) {
i = LINESIZ - i;
bcopy(rp, dp, i);
dp += i;
if ((rp += i) >= endring)
rp = ring;
}
*dp++ = '\r';
*dp++ = '\n';
if (write(s, text, dp - text) != dp - text)
break;
}
exit(0);
}
/* ARGSUSED */
chargen_dg(s, sep) /* Character generator */
int s;
struct servtab *sep;
{
char text[LINESIZ+2];
register int i;
register char *rp;
static char *rs = ring;
struct sockaddr sa;
int size;
if (endring == 0)
initring();
size = sizeof(sa);
if (recvfrom(s, text, sizeof(text), 0, &sa, &size) < 0)
return;
rp = rs;
if (rs++ >= endring)
rs = ring;
i = MIN(LINESIZ - 2, endring - rp);
bcopy(rp, text, i);
if ((rp += i) >= endring)
rp = ring;
if (i < LINESIZ - 2) {
bcopy(rp, text, i);
if ((rp += i) >= endring)
rp = ring;
}
text[LINESIZ - 2] = '\r';
text[LINESIZ - 1] = '\n';
(void) sendto(s, text, sizeof(text), 0, &sa, sizeof(sa));
}
/*
* Return a machine readable date and time, in the form of the
* number of seconds since midnight, Jan 1, 1900. Since gettimeofday
* returns the number of seconds since midnight, Jan 1, 1970,
* we must add 2208988800 seconds to this figure to make up for
* some seventy years Bell Labs was asleep.
*/
long
machtime()
{
struct timeval tv;
if (gettimeofday(&tv, (struct timezone *)0) < 0) {
fprintf(stderr, "Unable to get time of day\n");
return (0L);
}
return (htonl((long)tv.tv_sec + 2208988800));
}
/* ARGSUSED */
machtime_stream(s, sep)
int s;
struct servtab *sep;
{
long result;
result = machtime();
(void) write(s, (char *) &result, sizeof(result));
}
/* ARGSUSED */
machtime_dg(s, sep)
int s;
struct servtab *sep;
{
long result;
struct sockaddr sa;
int size;
size = sizeof(sa);
if (recvfrom(s, (char *)&result, sizeof(result), 0, &sa, &size) < 0)
return;
result = machtime();
(void) sendto(s, (char *) &result, sizeof(result), 0, &sa, sizeof(sa));
}
/* ARGSUSED */
daytime_stream(s, sep) /* Return human-readable time of day */
int s;
struct servtab *sep;
{
char buffer[256];
time_t time(), clock;
char *ctime();
clock = time((time_t *) 0);
sprintf(buffer, "%s\r", ctime(&clock));
(void) write(s, buffer, strlen(buffer));
}
/* ARGSUSED */
daytime_dg(s, sep) /* Return human-readable time of day */
int s;
struct servtab *sep;
{
char buffer[256];
time_t time(), clock;
struct sockaddr sa;
int size;
char *ctime();
clock = time((time_t *) 0);
size = sizeof(sa);
if (recvfrom(s, buffer, sizeof(buffer), 0, &sa, &size) < 0)
return;
sprintf(buffer, "%s\r", ctime(&clock));
(void) sendto(s, buffer, strlen(buffer), 0, &sa, sizeof(sa));
}